There are various forms of well known pipe bender available, one of which includes a main die forming part of or mounted on a body, the main die having a part-annular concave groove on its periphery. A circular shaping die having an annular concave groove on its periphery is rotatable about its own axis, which is parallel to the axis of the main die, the shaping die being supported on a mounting so that it is rotatable about the axis of the main die. The mounting can be driven by hand or by a reduction gear.
Such a pipe bender is very satisfactory for the actual operation of bending a pipe and the only difficulty arises in bending the pipe accurately by the right amount at the right place. This has hitherto been determined largely by the skill of the operator.